Dynomotion Forum

So I've finally succumbed and am building a small CNC plasma table using a 3D printed design.
I'm treating it as an experiment, but hoping it will work well. Worst case scenario, is I have to redesign it to remove the plastic.

Anyway, I currently have a spare KFlop, Kanalog, and Knozz kicking around.
A Kogna would probably be a better option, but I can't quite justify that at the moment.

However, I really need THC functionality, as the main parts I'll be cutting won't be flat.
I have ordered a voltage divider for the Plasma, but it's not going to provide any isolation.
I'm aware Mesa do Plasma input boards that convert the analogue to a PWM signal with isolation, but it's quite expensive and still needs extra components to get a KFlop suitable input.

So I've been doing a bit searching.
TI do the AMC1350 chip.
It takes a +/-5V analogue input, and provides an isolated +/-2V output. Add a DCDC converter for the required isolated supply, along with the required resistors/capacitors, and it should feed nicely into a suitable analogue input.

However, does anybody know of any other options I could be looking at?

Hi Moray,

That all sounds very reasonable to me.

One thought I had was to use an opto isolated analog output (such as the one on KNozz). Then use a comparator to compare this analog voltage to the THC voltage. Then connect comparator output to an opto isolated input. KFLOP software could then determine the THC voltage by ramping up/down the analog output until the comparator changes. Not as fast as an isolated ADC but probably fast enough for THC.